Fraction Blocks
Update: I've produced a new version of these blocks. This thing has the new blocks and a link to the Python/OpenSCAD source I used to make them. The new set has more fractions. The other main reason to take a look is that the labels on the fractions are embossed rather than debossed which makes it easier to print the labels in a different color or to highlight with some paint.
I made these blocks for my son. My hope is to support an experimental understanding of fractions. There've been a couple remixes provided by other makers. There's the missing 1/2 block and an cover.